Extreme compound events in the equatorial and South Atlantic

Area of Science:

• Marine biology
• Oceanography
• Climate science

Background:

• Marine ecosystems face amplified impacts from marine heatwaves (MHWs) when combined with other extreme events.
• Understanding the interplay of multiple stressors is crucial for predicting ecosystem responses.

Purpose of the Study:

• Investigate the spatiotemporal evolution of triple compound events (MHW, high acidity, low chlorophyll) in the equatorial and South Atlantic.
• Analyze the drivers behind these compound extreme events in different Atlantic regions.

Main Methods:

• Utilized observation-based datasets and reanalysis products to analyze past and present oceanographic conditions.
• Examined the frequency, intensity, and spatial distribution of triple compound events over the last two decades.
• Identified regional drivers, including frontal shifts, ocean heat transport, air-sea interactions, and upwelling dynamics.

Main Results:

• The frequency and intensity of triple compound events have significantly increased in the past two decades, with a recent peak.
• Regional drivers include poleward shifts of fronts (Angola Front, Brazil-Malvinas Confluence), increased Indian Ocean warm water inflow (Agulhas Leakage), altered air-sea heat fluxes (western equatorial/subtropical Atlantic), and weakened upwelling (eastern equatorial Atlantic).
• Triple compound events are widespread in the South Atlantic during El Niño events.

Conclusions:

• Triple compound events pose a growing threat to Atlantic marine ecosystems.
• El Niño Southern Oscillation (ENSO) events are linked to widespread triple compound events, offering potential for MHW prediction.
• Understanding regional drivers is key to mitigating the impacts of compounding climate extremes.